Electrical distribution systems can have or develop high resistance in wiring, connections, or components. Wiring can be sized improperly. Splices from wire to wire can be installed improperly. Connections between wires and wiring devices (outlets, connectors, circuit breakers, fuses, sockets, etc.) can become loose through vibration, improper installation, or time. Connections can also corrode due to the effects of the environment on the connection, or from electrolytic corrosion due to the improper selection and combination of aluminum and copper components. Two negative effects result from this high resistance.
One negative effect is resistive heating that can occur at higher load currents in the circuit. If the source of high resistance gets hot enough to ignite nearby combustible items, a fire can result. The National Fire Protection Association (NFPA) compiles data on fires and their causes. Recent statistics from the NFPA show that electrical distribution equipment is the fifth leading cause of home fires, the fourth in fire deaths, and the third leading cause of direct property damage in home fires.
The second negative effect is the voltage drop that can occur in a circuit downstream of the high resistance. Voltage drops are especially troublesome for computers, which can lose data during even momentary dips in supply voltage.
Inexpensive alternating current circuit and outlet testers are available in a number of configurations. Some test for connection of hot, neutral, and ground leads to the correct outlet terminals. Others test for capability of a ground fault circuit interrupter (GFCI) to operate properly. Still others test the capability of the ground conductor to carry current. Some have combinations of the above mentioned capabilities, but no tester retailing at a price attractive to consumers includes any provision for testing the capability of the circuit or outlet to carry a load. There is a device (U.S. Pat. No. 4,857,826) sold to professional electricians that can test the load-carrying ability of an outlet, but the device includes many other tests as well, and sells for more than four hundred dollars.
Accordingly, the primary object of this invention is to provide a tester which can detect percentage voltage drop in electrical circuits and outlets due to an applied load, is simple both to use and to manufacture, and yet can be marketed at a price that is attractive to consumers.